Replacing rns-e with nexus 7 in an AUDI S4 B7 (2008)

Hi all,

I am replacing my rns-e with my nexus 7 tablet. I made the box for it and the power converters, haven't tried them yet cause I am stuck with the sound

I made a headphone jack to 8pin wire to hook up on the c-block of my harness, where the pin out on the rns-e says line out, I did this because I don't have an a-block(???) so I guessed that's where the Bose amp gets audio from the unit. I hooked the cable in and played music on my nexus 7, but nothing... Reading around I guess I have to turn the amp on, but I haven't found anywhere what pin to hook up and what signal to send, any thoughts??